In recent years, a variety of tablet display devices, which overcome such defects of a cathode ray tube (CRT) as heavy weight and large size, have been developed. Such tablet display devices include liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), and organic light-emitting diode (OLED) displays.
In the above tablet displays, the OLED displays, which employ the organic light-emitting diodes and emit light via recombination of electrons and holes to display images, have a high response speed and are driven with a low power consumption. In addition, the OLED displays have good light-emitting efficiency, luminance and view angle, and thus have become a focus in the related field.
Generally, according to the driving method of the organic light-emitting diodes, the organic light-emitting diode displays are categorized into passive matrix organic light-emitting diodes (PMOLEDs) and active matrix organic light-emitting diodes (AMOLEDs).
A passive matrix organic light-emitting diode employs a method in which anodes and cathodes form a crossed format and the cathode lines and anode lines are selectively driven, whereas an active matrix organic light-emitting diode employs a method in which thin-film transistors and capacitors are integrated in each pixel and the voltage is maintained by the capacitors. The passive matrix organic light-emitting diode has a simple structure and a low cost, but a large-size and high-precision panel is hard to be obtained with this kind of diode. Comparatively, a large-size and high-precision panel may be obtained with the active matrix organic light-emitting diode. However, a control method of the active matrix organic light-emitting diode is hard to be implemented technically, and a relatively high cost is needed.
With respect to the resolution, contrast and operation speed, currently there is a tendency that an active matrix organic light-emitting diode (AMOLED) display in which respective unit pixels are selectively turned on or turned off is used.
As illustrated in FIG. 1, a conventional active matrix organic light-emitting diode (AMOLED) display device includes pixels P1, . . . , P6, a data driver 10, and a selector 20 including a plurality of data selection switches S1, . . . , S6. The data driver 10 transmits corresponding data signals to the pixels P1, . . . , P6 via data lines D1, . . . , D6, wherein transmission of the data signals from the data driver 10 to the pixels P1, . . . , P6 is controlled by the level waveforms of control signals SW1, . . . , SW6 of the data selection switches S1, . . . , S6. FIG. 2 is a schematic diagram of level waveforms of the control signals SW1, . . . , SW6 in FIG. 1. When the control signals SW1, . . . , SW6 stay in a low level, the data selection switches S1, . . . , S6 are switched on. In this case, the data signals output by the data driver 10 may be transmitted to the pixels P1, . . . , P6 for image display, and the pixels P1, . . . , P6 retain the voltages corresponding to the data signals. With the restriction of the features of the AMOLED, if the data signals with a high voltage output by the data driver 10 is transmitted to the pixels P1, . . . , P6 in a previous image display segment, then the data signals with a low voltage output by the data driver 10 cannot be transmitted to the pixels P1, . . . , P6 in a next image display segment. To prevent the problem that the data cannot be written into the pixels, a low voltage needs to be pre-charged before an image is displayed. At present, pre-charging low voltage is implemented and controlled by adjusting the level waveforms of the control signals SW1, . . . , SW6 and the level waveforms of the data signals output by the data driver 10. As illustrated in FIG. 2, before the data driver 10 transmits the data signals to the pixels P1, . . . , P6, all the data selection switches S1, . . . , S6 are controlled to be switched on by maintaining the control signals SW1, . . . , SW6 all in a low level, and the data driver 10 is controlled to simultaneously output a low voltage to implement the pre-charging of low voltage. However, the time sequence of the data signals output by the data driver 10 and the time sequence of the control signals of the data selection switches S1, . . . , S6 are complicated, which increases the power consumption of the data driver 10.